I know that this thread is pretty old now, but I wanted to share the conclusion to this episode.....first trip down, I took some cerium oxide polish, made by 3M. I used a buffer on an electric drill. After working it for hours, and not making progress I took it to a local detailer, and the owner set a guy buffing for about 2 days (not exaggerating)........ Marginal improvement at best.
So............next trip.......... I bought a new windsheild at a autoglass place in California. Built a box, and checked it in with American Airlines. The part I was worried about was getting it through Brazilian customs......... sweating like a drug smuggler I walked right through customer.....didn't get checked!
So after 2 more internal flights, and a 5 hour car ride I got it (in one piece) to the vehicle in question.
If you find yourself with bat streaks on your windsheild, its not worth the effort of trying to buff them out. Mine were deep etchings, and it required a new windshield.
The great part is the jeep now looks awesome! I had it resprayed and it looks like a million bucks.